1. Field of the Invention
The present invention relates to real-time video conferencing. More specifically, the invention relates to a system that facilitates flexible real-time video conferencing among a plurality of users by providing multilayer keying of multiple video images.
2. Description of Related Art
Video teleconferencing occurs when people in different locations send voice and video data to each other in order to simulate having all of the participants present in a single room. Each person in a multi-point conference wants to see all or most of the other participants. Accordingly, the various video streams are presented to each participant in a spatially separate manner, either on separate screens or in separate areas of a single video display. Each of the video conferencing terminals sends a locally generated video image to each of the other participant terminals and receives a video image from each of the other participants. In the prior art, this meant that for a three-way conference, six video streams must be transmitted; for a five-way conference, twenty video streams must be transmitted; for an eight participant conference, fifty-six video streams must be transmitted, and so on. Generally, if N people are holding a televideo conference, then N.times.(N-1) transmission channels must be used. Accordingly, the relatively large number of channels used for a video teleconference involving multiple participants becomes prohibitive with the prior art systems.
Furthermore, participants must have a sufficient number of input channels, decoders, and translators (if transmitting different video formats) to receive and display multiple images from different participants. Accordingly, the required number of channels, decoders, and/or translators also becomes prohibitive.
With the prior art systems, video conferencing participants were unable to customize their video display by keying in or out portions of the displayed image, or by making the various images of participants overlap in a natural-looking manner, or place and size images as they like. The participants were also unable to associate video images with other multimedia objects to enhance the variety of conferencing functions that can be enjoyed.